This R13 conference grant application requests funds to support the XXIInd North American Testis Workshop that will be held from April 13 to April 16, 2013 in San Antonio, Texas. Since 1972, the North American Testis Workshop has been the premiere international forum for bringing basic and clinician-scientists together to present and discuss the most recent findings on the regulation and function of the fertile and infertile testis The first goal of this meeting is to promote solutions for two major medical and public health problems: the high incidence of male infertility in the developed world and the lack of a safe and reversible male contraceptive. Another important goal of this meeting is to foster the development of future leaders in this field, especially if they currently are trainees, or if they re women or underrepresented minorities. The theme of the XXIInd North American Testis Workshop is, The Foundations of Male Fertility. The program includes three major lectures: the keynote address, the benchmark lecture, and the European Molecular Biology Organization Young Investigator Lecture. There also will be 18 invited talks, which are grouped in five sessions. Session 1 is: Regulation and Restoration of Fertility in Men; Session 2 is: Genome Integrity; Session 3 is: Regulation of Gene Expression; Session 4 is: Somatic Cells; and Session 5 is: Stem Cells and Their Niche. In addition to the invited talks, each session will end with two short talks from abstracts that are submitted by young investigators (trainees and Assistant Professors who have been in rank for no more than 2 years.) The meeting also includes two poster sessions, and the posters will remain on display throughout the meeting. The keynote address begins the meeting and sets its tone. Dr. David Zarkower, Professor of Cell Biology and Genetics at the University of Minnesota, will present this lecture. Dr. Zarkower is one of the world's leading experts in the molecular and genetic control of sex determination. His research focuses on the function of DMRT1 and other DM-domain genes in sex determination of metazoans. As the key event in testis determination is the formation of Sertoli cells, his talk provides a foundation for Session 4, Somatic Cells. Additionally, recent evidence indicates that mutations in the DMRT1 gene cause testicular cancer, a subject that is addressed in Session 2. The benchmark lecture highlights major advances in our understanding of testis regulation that are achieved through use of state-of-the-art technologies. Dr. Michael Griswold, Regents Professor, Washington State University, will present a genome-wide perspective on the regulation of spermatogenesis. Dr. Griswold pioneered the use of microarrays in the study of spermatogenesis and is now applying deep sequencing for a more detailed view of the changes in gene expression during male germ cell development. His talk will provide a foundation for Session 3. Dr. Antoine Peters of the Friedrich Miescher Institute will present The European Molecular Biology Organization Young Investigator Lecture. This lecture will address the epigenetic regulation of germ cell development, a topic that is also addressed in Session 3. A notable aspect of the program is the topic of Session 1, Regulation and Restoration of Fertility in Men. The Program Committee decided to begin with this topic in order to stimulate discussion throughout the meeting on the translation of basic studies in testis regulation and function to the treatment of infertile men and the development of male contraceptives. Presentations in the subsequent four sessions complement those in Session 1. In this application, we request funds to partially defray the cost of attendance of the 10 young investigators whose abstracts will be selected for short platform talks. The rest of the funds will defray part of the housing costs for the 20 distinguished scientists who have been invited to speak at this meeting.